1. Field of the Invention
The present invention relates to a medical device and more particularly to an in-vivo medical device for use during external beam radiation therapy (EBRT).
2. Description of the Related Art
Radiation for breast cancer is most often accomplished by the use of full breast radiation. This imparts radiotherapy to the entire area of the breast. Radiation of the breast will necessarily involve surrounding structures such as, but not limited to, the heart, lungs, esophagus, chest wall, ribs and other structures that are in close proximity to the breast. Thus, a new concept of only partial breast radiation has grown in popularity and involves the use of balloon catheters to treat cancer in the lumpectomy cavity. Studies thus far indicate that it is as effective as full breast radiation and eliminates damage to the surrounding organs.
Partial breast radiation is currently being delivered through balloon catheters placed into the lumpectomy cavity at the time of surgery or later under ultrasound guidance. This process of using a balloon catheter for radiation treatment involves placing a radioactive seed or source down the indwelling catheter for a brief period of time. Unfortunately, this method of utilizing a catheter and radioactive seed has a number of drawbacks. For instance, utilizing a concentrated dose of radiation over a short period of time in the form of a radioactive seed planted through means of the catheter creates a multitude of side effects such as fat necrosis, seromas, hematomas, infection and undesirable cosmetic outcomes. The use of partial breast radiation balloon catheters also requires additional expensive equipment to maintain and direct the source of the radiation into the partial breast balloon catheter, which is not available at all radiation sites.
Currently, the other source of breast radiation is full breast radiation by external beam equipment. The external beam radiation equipment is excellent for solid organs such as the liver that contains a small tumor or the head of the pancreas that contains a small tumor. These tumors are most effectively treated with external beam radiation by placing a target or a metallic marker into the area of the tumor, which allows the external beam to be focused on this tumor and avoid damage to the surrounding tissue. These solid organs are rigid and do not move during the radiation treatment. But the breast is an external structure, consisting primarily of fatty tissue, unlike the liver and pancreas.
Of note, the use of metallic markers in the breast tissue creates an unstable environment for the marker, and the marker does not necessarily remain in place or in a constant location. Consequently, in fatty tissue, these small seeds or targets may move from the intended target site, rendering the therapy ineffective. Thus, in order to utilize external beam radiation on the breast, a stable target must be available.